Lower the priority of shared workers

content/browser/worker_host/worker_service_impl.cc

Index: content/browser/worker_host/worker_service_impl.cc
diff --git a/content/browser/worker_host/worker_service_impl.cc b/content/browser/worker_host/worker_service_impl.cc
index 703b31f02ce3b7f2df5423c95c9c37b528c1a923..18c4350dfb40c760b60a401ac506401f11dc13b1 100644
--- a/content/browser/worker_host/worker_service_impl.cc
+++ b/content/browser/worker_host/worker_service_impl.cc
@@ -10,12 +10,20 @@
 #include "base/logging.h"
 #include "base/threading/thread.h"
 #include "content/browser/devtools/worker_devtools_manager.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/worker_host/worker_message_filter.h"
 #include "content/browser/worker_host/worker_process_host.h"
 #include "content/common/view_messages.h"
 #include "content/common/worker_messages.h"
 #include "content/public/browser/child_process_data.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_types.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/resource_context.h"
+#include "content/public/browser/web_contents.h"
 #include "content/public/browser/worker_service_observer.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/process_type.h"
@@ -25,6 +33,180 @@ namespace content {
 const int WorkerServiceImpl::kMaxWorkersWhenSeparate = 64;
 const int WorkerServiceImpl::kMaxWorkersPerTabWhenSeparate = 16;
 
+class WorkerPrioritySetter
+    : public NotificationObserver,
+      public base::RefCountedThreadSafe<WorkerPrioritySetter> {

[darin (slow to review), 2013/05/11 06:02:19]

should you indicate a thread on which this object should be deleted?  is it safe
to delete a NotificationRegistrar on any thread?  i thought that had to die on
the UI thread.

[shatch, 2013/05/13 17:47:47]

Done.

+ public:
+  WorkerPrioritySetter();

[jam, 2013/05/28 14:28:30]

nit: since this class is all in the cc file, why split the declaration from the
definition? i find it more readable if they're together, but since this is just
personal style, i leave it ultimately to you

[shatch, 2013/05/28 17:52:13]

I guess it was the opposite for me, find it easier to follow if split

[jam, 2013/05/28 17:56:18]

ok, up to you since this is personal style and not in the style guide :)

+
+  // Invoked by WorkerServiceImpl when a worker process is created.
+  void NotifyWorkerProcessCreated();
+
+ private:
+  friend class base::RefCountedThreadSafe<WorkerPrioritySetter>;
+  virtual ~WorkerPrioritySetter();
+
+  // Posts a task to perform a worker priority update.
+  void PostTaskToGatherAndUpdateWorkerPriorities();
+
+  // Gathers up a list of the visible tabs and then updates priorities for
+  // all the shared workers.
+  void GatherVisibleIDsAndUpdateWorkerPriorities();
+
+  // Registers as an observer to receive notifications about
+  // widgets being shown.
+  void RegisterObserver();
+
+  // Sets priorities for shared workers given a set of visible tabs (as a
+  // std::set of std::pair<render_process, render_view> ids.
+  void UpdateWorkerPrioritiesFromVisibleSet(
+      const std::set<std::pair<int, int> >* visible);
+
+  // Called to refresh worker priorities when focus changes between tabs.
+  void OnRenderWidgetVisibilityChanged(std::pair<int, int>);
+
+  // NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details) OVERRIDE;
+
+  NotificationRegistrar registrar_;
+};
+
+WorkerPrioritySetter::WorkerPrioritySetter() {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(&WorkerPrioritySetter::RegisterObserver, this));
+}
+
+WorkerPrioritySetter::~WorkerPrioritySetter() {
+}
+
+void WorkerPrioritySetter::NotifyWorkerProcessCreated() {
+  PostTaskToGatherAndUpdateWorkerPriorities();
+}
+
+void WorkerPrioritySetter::PostTaskToGatherAndUpdateWorkerPriorities() {
+  BrowserThread::PostTask(
+      BrowserThread::UI, FROM_HERE,
+      base::Bind(
+          &WorkerPrioritySetter::GatherVisibleIDsAndUpdateWorkerPriorities,
+          this));
+}
+
+void WorkerPrioritySetter::GatherVisibleIDsAndUpdateWorkerPriorities() {
+  std::set<std::pair<int, int> >* visible_renderer_ids =
+      new std::set<std::pair<int, int> >();
+
+  // Gather up all the visible renderer process/view pairs
+  for (RenderProcessHost::iterator it =
+      RenderProcessHost::AllHostsIterator();
+      !it.IsAtEnd(); it.Advance()) {
+    RenderProcessHost* render_process_host = it.GetCurrentValue();
+    if (render_process_host->VisibleWidgetCount()) {
+      for (RenderProcessHost::RenderWidgetHostsIterator rit =
+           render_process_host->GetRenderWidgetHostsIterator(); !rit.IsAtEnd();
+           rit.Advance()) {
+        RenderWidgetHost* render_widget =
+            render_process_host->GetRenderWidgetHostByID(rit.GetCurrentKey());
+        if (render_widget) {
+          RenderWidgetHostView* render_view = render_widget->GetView();
+          if (render_view && render_view->IsShowing()) {
+            visible_renderer_ids->insert(
+                std::pair<int, int>(render_process_host->GetID(),
+                                    render_widget->GetRoutingID()));
+          }
+        }
+      }
+    }
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&WorkerPrioritySetter::UpdateWorkerPrioritiesFromVisibleSet,
+                 this, base::Owned(visible_renderer_ids)));
+}
+
+void WorkerPrioritySetter::UpdateWorkerPrioritiesFromVisibleSet(
+    const std::set<std::pair<int, int> >* visible_renderer_ids) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));

[darin (slow to review), 2013/05/11 06:02:19]

nit: How about adding more DCHECKs like these to other methods?

[shatch, 2013/05/13 17:47:47]

Done.

+
+  for (WorkerProcessHostIterator iter; !iter.Done(); ++iter) {
+    if (!iter->process_launched())
+      continue;
+    bool throttle = true;
+
+    for (WorkerProcessHost::Instances::const_iterator instance =
+        iter->instances().begin(); instance != iter->instances().end();
+        ++instance) {
+
+      // This code assumes one worker per process
+      WorkerProcessHost::Instances::const_iterator first_instance =
+          iter->instances().begin();
+      if (first_instance == iter->instances().end())
+        continue;
+
+      WorkerDocumentSet::DocumentInfoSet::const_iterator info =
+          first_instance->worker_document_set()->documents().begin();
+
+      for (; info != first_instance->worker_document_set()->documents().end();
+          ++info) {
+        std::pair<int, int> id(
+            info->render_process_id(), info->render_view_id());
+        if (visible_renderer_ids->find(id) != visible_renderer_ids->end()) {
+          throttle = false;
+          break;
+        }
+      }
+
+      if (!throttle ) {
+        break;
+      }
+    }
+
+    iter->SetBackgrounded(throttle);
+  }
+}
+
+void WorkerPrioritySetter::OnRenderWidgetVisibilityChanged(
+    std::pair<int, int> id) {
+  std::set<std::pair<int, int> > visible_renderer_ids;
+
+  visible_renderer_ids.insert(id);
+
+  UpdateWorkerPrioritiesFromVisibleSet(&visible_renderer_ids);
+}
+
+void WorkerPrioritySetter::RegisterObserver() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  registrar_.Add(this, NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED,
+                 NotificationService::AllBrowserContextsAndSources());
+  registrar_.Add(this, NOTIFICATION_RENDERER_PROCESS_CREATED,
+                 NotificationService::AllBrowserContextsAndSources());
+}
+
+void WorkerPrioritySetter::Observe(int type,
+    const NotificationSource& source, const NotificationDetails& details) {
+  if (type == NOTIFICATION_RENDER_WIDGET_VISIBILITY_CHANGED) {
+    bool visible = *Details<bool>(details).ptr();
+
+    if (visible) {
+      int render_widget_id =
+          Source<RenderWidgetHost>(source).ptr()->GetRoutingID();
+      int render_process_pid =
+          Source<RenderWidgetHost>(source).ptr()->GetProcess()->GetID();
+
+      BrowserThread::PostTask(
+          BrowserThread::IO, FROM_HERE,
+          base::Bind(&WorkerPrioritySetter::OnRenderWidgetVisibilityChanged,
+              this, std::pair<int, int>(render_process_pid, render_widget_id)));
+    }
+  }
+  else if (type == NOTIFICATION_RENDERER_PROCESS_CREATED) {
+    PostTaskToGatherAndUpdateWorkerPriorities();
+  }
+}
+
 WorkerService* WorkerService::GetInstance() {
   return WorkerServiceImpl::GetInstance();
 }
@@ -34,7 +216,9 @@ WorkerServiceImpl* WorkerServiceImpl::GetInstance() {
   return Singleton<WorkerServiceImpl>::get();
 }
 
-WorkerServiceImpl::WorkerServiceImpl() : next_worker_route_id_(0) {
+WorkerServiceImpl::WorkerServiceImpl()
+    : priority_setter_(new WorkerPrioritySetter()),
+      next_worker_route_id_(0) {
 }
 
 WorkerServiceImpl::~WorkerServiceImpl() {
@@ -457,6 +641,10 @@ void WorkerServiceImpl::NotifyWorkerDestroyed(
                     WorkerDestroyed(process->GetData().id, worker_route_id));
 }
 
+void WorkerServiceImpl::NotifyWorkerProcessCreated() {
+  priority_setter_->NotifyWorkerProcessCreated();
+}
+
 WorkerProcessHost::WorkerInstance* WorkerServiceImpl::FindSharedWorkerInstance(
     const GURL& url,
     const string16& name,